1. Field of the Invention
This invention relates to an apparatus for feeding a preferably multi-ply web of synthetic thermoplastics, which apparatus comprises a pair of feed rolls, which define a feeding nip and each of which is formed with annular grooves, and two scraping rakes, which are secured in the frame and have tines extending through the annular grooves, wherein at least one of said rakes is movably mounted and arranged to actuate a switch for stopping the drive for the rolls when the scraping rake is moved out of its normal position by the web because it is bulged.
2. Description of the Prior Art
German Utility Model 72 32 187 discloses an apparatus which is of the kind described hereinbefore and in which a rake is connected on both sides to arms, which by means of shafts are pivoted to the frame of the machine. At least one of said shafts carries a second arm, which is supported by a compression spring and which is pivotally movable against the force of the compression spring to actuate a microswitch. When the web moving through the feeding nip of the pair of rolls is bulged, that web will urge the pivoted upper scraping rake upwardly so that the microswitch is acturated to stop the drive for the feed rolls. It has been found in practice that in the operation of the known apparatus a considerable bulge in the web will be required before the scraping rake can be sufficiently deflected to actuate the microswitch. But it will be difficult to service the apparatus and to eliminate a defect when a considerable bulge must be eliminated after the microswitch has been actuated.